Rod outer segment (ROS) disk membranes stick to each other in stacks. Means of disaggregating the disk-disk adhesion without breaking the membrane will be studied. The molecule responsible for the adhesion will be further purified and its properties studied. Studies in progress to determine the topological membrane sidedness of rhodopsin and lipid head groups using membrane impermeable reagents and proteolytic enzymes will be completed. Analysis of low angle xray diffraction of the ROS as a function of time after bleaching will be carried out. The electron density profiles of the membranes, corrected for lattice and substitution disorder will be analyzed. A functional assay for the ROS disk membrane will be sought using improved disk preparations.